Multiparameter lighting fixtures are lighting fixtures, which illustratively have two or more individually remotely adjustable parameters such as focus, color, image, position, or other light characteristics. Multiparameter lighting fixtures are widely used in the lighting industry because they facilitate significant reductions in overall lighting system size and permit dynamic changes to the final lighting effect. Applications and events in which multiparameter lighting fixtures are used to great advantage include showrooms, television lighting, stage lighting, architectural lighting, live concerts, and theme parks.
Multiparameter lighting fixtures are commonly constructed with a lamp housing that may pan and tilt in relation to a base housing so that light projected from the lamp housing can be remotely positioned to project on a stage surface. The lamp housing of the multiparameter light contains the optical components such as a lamp and includes color filters for varying the color of the projected light. Commonly a plurality of multiparameter lights are controlled by an operator from a central controller. The central controller is connected to communicate with the plurality of multiparameter lights via a communication system.
U.S. Pat. No. 4,962,687 to Belliveau, describes a variable color lighting system and instrument that uses an additive color mixing method to fade from one color to another. The lighting instrument is comprised of three lamps each emitting a different wavelength of light in the colors of red, green and blue that can be added together to vary the color of the projected light.
The use of dichroic filters to color the light projected by a multiparameter theatre lighting instrument is known in the art. U.S. Pat. No. 4,392,187 to Bornhorst, discloses the use of dichroic filters in a multiparameter light. Bornhorst discloses “The dichroic filters transmit light incident thereon and reflect the complement of the color of the transmitted beam. Therefore, no light is absorbed and transformed to heat as found in the prior art use of celluloid gels. The use of a relatively low power projection lamp in lights 30 and 110 substantially reduces the generation of infrared radiation which causes high power consumption and heat buildup within prior art devices.” While the use of color wheels that support multiple wavelengths of dichroic filters to color the light of a multiparameter stage light is still in common practice, it is also common practice to construct a multiparameter light having variable density dichroic filter flags that gradually color the light using a subtractive color method. The subtractive color method may use the dichroic filter flag colors of cyan, magenta and yellow to gradually and continuously vary the color of today's multiparameter stage light producing a pleasing color fade when visualized by an audience. The gradual and continuous varying of cyan, magenta and yellow in the light path of a multiparameter light is referred to as “CMY color mixing” in the theatrical art.
U.S. Pat. No. 6,687,063 to Rasmussen discloses a dichroic color mixing flag in FIGS. 8 and 12 with dichroic etched fingers that operate to produce a variable color as they are translated across the light created by the optical path.
U.S. Pat. No. 8,220,969 to Bornhorst describes a color changing structure for a theatrical instrument that is a wheel that varies saturation from its outside towards its inside.
Bornhorst describes the limitations of the known CMY color mixing systems as follows: “A CYM mixing system can be formed using three patterned color wheels that subtractively create color in a way that is similar to that used by the print industry. Three cylindrical circular glass wheels are each coated, respectively, with cyan, magenta, and yellow, e.g. using a dichroic filter stack. The wheels are patterned using photolithographic and chemical etch techniques to remove parts of the filter coating and selected areas. The completed wheel has a completely uncoated area that allows white light to pass. At the opposite extreme, the wheel has a completely coated area that fully saturates the color of the beam. A density patterned area is in between the two, which has a variable saturation gradient.
The wheels may be used in pairs or in triples to create partial color limited continual color range. For example, the magenta wheel may be used in combination with the yellow wheel, to generate the entire range of yellow to orange to red to magenta colors.
While this system produces good color, the inventor has recognized that this system is inherently limited in the color space it can produce. A color space is defined by the cyan, yellow and magenta filters. The color space can be modified by selecting different color points for the filters, but the space remains limited. The inventor recognized that this is particularly weak in producing saturated colors.” (Bornhorst, col. 2, ln. 48-col. 3, ln. 5)
Present day light sources for theatrical instruments are primarily comprised of light emitting diodes (LEDs). One such theatrical instrument using a high power white LED light source is the SolaWash 2000 by High End Systems of Austin, Tex. found at https://www.highend.com/products/lighting/solawash. This high power white LED lighting instrument varies the color of the projected light using a CMY color mixing system, which is known. The diameter of the light path from the white LED source that is created by the optics where the light path travels through the CMY color mixing flags is approximately 50 millimeters (mm). Unfortunately the large diameter light path excludes the invention described by Bornhorst because a wheel diameter of the Bornhorst invention would need to approximate 300 millimeters (mm) in diameter to be effective and efficient.
Present day theatrical lighting designers can be disappointed by the known CMY color mixing system. Not only does the known CMY color mixing system have a limited saturation color pallet, the known CMY color mixing system is also compromised in the ability to create a wide color pallet of pastels. Pastels colors are requirement in theatre and opera where lighting designers can feel that pastel colors are less distracting to an audience and are better for skin tones.